Air pressure water system



Oct. 5, 1948. s. o. CARLSON AIR PRESSURE WATER SYSTEM Filed Jan. 19,1946 V Q l vq qwl W W 9% 3w 6 T m I W Q a \\\\.M E mm mm; \w 0 \w d Q mmQ v Patented Oct. 5, 11948 UNITED STATES I PAT ENT OFFICE This inventionrelates generally to air-pressure water supply systems of the typeembodying a pump for delivering water from a source of supply to apressure tank from which the water is distributed by air pressure, andin particular -to a device for feeding air into the tank to maintain adesired air pressure in the tank.

invention will become apparent from the following description whentake'nin connectionwith the accompanying drawing in which:

An object of this invention is to provide an improved air feed devicefor an air pressure water sytem of the above mentionedtype.

Yet another object of this invention is to provide an air feed devicefor the ressure tank in an air pressure water system which is adaptedfor connection only to the tank and operable in response to pressurechanges in the tank.

A further object of this invention is to provide an air feed device forthe pressure tank in an air pressure water system which is comprised ofa relatively few number of parts, of a compact construction adapted forassembly as a unit with a pressure tank, efllcient in operation tocontinuously supply air to the tank to compensate for normal air lossesfrom the tank, and capable of operating over prolonged periods of timewith a minimum of servicing attention. v

A feature of this invention is found in the pro vision of an air feeddevice for the pressure tank of an air pressure water supply system inwhich a check-valved piston for delivering air to the tank operatesagainst and into a water head whereby all of the air acted upon by thepiston is positively and completely exhausted during each full workingstroke of the piston.

Yet another feature of this invention is found in the provision of anair feed device for an air pressure water supply system in whicha'single Fig. 1 is a longitudinal sectional view of the air feeddevice'of this invention shown embodied in anair-pressure water. supplysystem;

Fig. 2 is a reduced longitudinal sectional view of the air feed devicewith parts shown in changed position relative to their showing in Fig.1;

Figs. 3 and 4 are illustrated similarly to Fig. 2 but with parts thereofshown in changed position; and

Figs, 5, 6 and 7 are sectional detail views of valve units illustratedgenerally in Fig. 1.

With reference to the drawings the air feed device of this invention,indicated generally as' in in Fig. 1', is shown embodied in an airpressure water supply-system including a pump'l I, a motor i2 foroperatingthev pump and a pressure tank l3. The motor i2 is an electricmotor adapted to be connected in a well-known manner with a source ofelectrical supply, and includes a control switch I4 air connected withthe top of the tank i3 through a pipe i6 and operable in response to theair pressure in the tank to provide for an automatic operation of themotor [2, and in turn of the pump II, to maintain a desired water supplyin the tank. The pump II has an inlet pipe I], connectible with a sourceof water supply, and an outlet I8 connected to the bottom of the tank l3by a pipe 19.

The air. feed device Ill comprises a cylindrical casing 2| formed witha'pair of co-axial cylinders cylinder with a pair of cylinder portionsof different diameters has a piston structure movable in one direction,in response to an increase of pres.- sure in the tank, to effect apressure build up in the larger cylinder portion, and movable in anopposite direction by the built up pressure as the pressure in the tankis decreased. Air admitted into the small cylinder, on movement of thepiston structure in response to the pressure increase in the tank, isdelivered to the large cylinder and then into the tank as the pistonstructure is moved in response to the pressure built up in the largecylinder portion. A bypass conduit in the small cylinder portion, aftera predetermined travel of the piston structure. admits water from thetank into the small cylinder portion so as 22 and 23 open'to each otherat their inner ends, and with the cylinder 22 of a'smaller diameter thanthe cylinder 23. The outer ends ofthe cylinders 22 and 23 are closed byend walls 24 and 23,-respectively.

Operable within the casing 2| is a iston structure comprising a piston21- for the cylinder 22,

and a piston 28 for the cylinder 23. A hollowv member or tube 29connects the pistons 21 and 28 for movement together. One end 3| 'of thetube 29 is extended through the piston 28 and is connectedto such pistonby locking nuts 32 threadable on the tube end 3i against oppositesidesof the piston 28. With the tube end 3i extended through the piston 28 itis seen that the tube 29 is open to the cylinder 23 above the top side33 of the Pi ton 23 as viewed in Figs. 1, 2, 3, and4. The other end 34of the tube 29-is received in an annular recess 36 formed in the to side31 of I the piston 2l,las viewedinF-igs. 1-4,. and 6. It is thus seenthat'the tube 29 is in a spaced relation within the casing 2l andrigidly connects the pistons 21 and 28 for concurrent reciprocalmovement.

Fluid communication between the tube end 34 Y and the lower side 38 ofthe piston 21 is controlled by a check valve 39 including a tube 4|having its lower end threadable in a threaded opening 42 in the piston21. A valve seat 43, within the tube 4 I, cooperates with a valve member44 having a stem 46 loosely extended through an opening 41 formed in astop 48 carried in the upper end of the tube 4| and adapted to limit theupward movement of the valve member 44. On opening of the check valve39, therefore, fluid is admitted from the lower side of the piston 21into the tube 23 for passage into the cylinder 23 above the piston 28.

Air for feeding into the tank I3 is admitted into the cylinder 22 to thelower side 38 of the piston 21 by an air check valve indicated generallyin Fig. l as 49 and shown in detail in Fig. 7, The valve 49 is of ausual type and includes a tube i threadable into a threaded opening 52in the outer end wall 24 of the cylinder 22. A valve seat 53, within thetube 5i, is open to the atmosphere and is associated with a valve member54 having a stem 56 loosely extended through opening 51 formed in a stopmember 58 carried in the tube 5|. The valve member 54 is normallyretained in a seated position on the valve seat 53 by a spring 59mounted about the valve stem 56. On an upward travel of the piston 21the pressure within that portion of the cylinder 22 below the piston 21is reduced to a sub-atmospheric pressure whereby the valve member 54 isopened to admit atmospheric air into the cylinder 22.

For a purpose which will appear later the cylinder 22 is providedintermediate its ends and on its outer periphery with a boss member 6|having a fluid passage 62 arranged with its opposite ends 63 and 64 ataxially spaced positions on the cylinder 22 and open to such cylinder.

The casing 2| is supported on the tank 13 by a radially extended pipe 66open at one end to the casing 2| at substantially the junction of thecylinders 22 and 23, and having its opposite end 61 open to the tank l3and threadable in a sidewall thereof. The tube 66, and in turn the tank13, is in fluid communication with the cylinder 23 at a positionintermediate the ends thereof, by the provision of a fluid conduit orpipe member 68. Arranged in the pipe 68 is a check valve 69 (Figs. 1 and5) adapted to control the flow of fluid from the cylinder 23 through thepipes 68 and 66 into the tank l3. The check valve 69 includes a casing1| having a partition wall 12 formed with a valve seat 13. A valvemember 14, responsive in operation to the pressures in the cylinder 23and in the tank I3, is moved to a seated position with the valve seat 13when the pressure in the tank l3 exceeds the pressure in the cylinder23, and is unseated when the pressure in the tank I3 is less than thepressure in the cylinder 23.

In the operation of the device of this invention to feed air into thetank [3 to replace normal air losses from the tank, assume the tank l3to be empty of water and the pistons 21 and 28 in their positions shownin Fig. 1. At these positions of the pistons the check valves 39, 43 and69 are in their closed positions illustrated in Figs; 6,7 and 5,respectively. On operation of the pump H by the motor l2 water isdelivered to the tank l3 through the pipe I 9. As the level of thewater, indicated as 16, rises in the tank i3, the air within the tank iscompressed between the water 16 and the top of the tank 13. It isapparent, of course, that the increase in air pressure within the tankvl3 takes place progressively with an increase in the height of the waterlevel within the tank.

Until the water reaches the level of the pipe or tube 66 air in thecasing 2| between the pistons 21 and 28 is at the same pressure as theair in the tank I3. However, passage of air into'the cylinder 23 throughthe pipe 68 is prevented by the check valve 69. Due to the difference inthe surface areas of the pistons 21 and 28 the pressure of the air inthe space 11, between the pistons 21 and 28, acts against the piston 28to move the piston structure upwardly within the casing 2|. This upwardmovement of the piston structure effects a sub-atmospheric pressure inthe cylinder 22 between the lower side'38 of the piston 21 and the endwall 24 of the cylinder 22. As a result of this sub-atmospheric pressurethe check valve 49 is opened to admit air at atmospheric pressure intothe space 18 formed below the piston 21 by the upward travel of thepiston structure.

When the water in the tank i3 reaches the level of the pipe 66 the airwithin the space 11 is replaced by water at the same pressure, with suchair being exhausted from the casing 2| through the pipe 66 into the topof the tank l3. When this condition occurs the parts of the device arein their relative positions shown in Fig. 2. On a continued supply ofwater into the tank i3 the piston 21 continues to provide for asub-atmospheric pressure on the space 18 and for the piston 28 tocompress the air within the cylinder 23.

In the event the air pressure in the cylinder 23, when the piston 28 isbelow the level of the end 8i of the pipe 68, is greater than thepressure within the tank 13 the valve 69 will open to admit air from thecylinder 23 into the tank through the pipes 63 and 66. On movement ofthe piston 28 above the level of the pipe end 8| equal pressures existat opposite sides of the valve 69 due to the fluid connection of thespace 11 with the tank l3 through the pipe 66.

As the air pressure in the tank I3 approaches a value of about fortypounds per square inch, which is a usual maximum pressure in a watersupply system of the type illustrated in Fig. 1, the piston 21 movesabove the level of the lower end 63 of the bypass 62, as illustrated inFig. 3. Water from the space 11 is thus admitted through the bypass 62into the space 1B-below the piston 21. As a result the pressure withinthe space '18 is increased above atmospheric pressure to ,pass 62. Whenthe piston 21 is substantially between the ends 63 and 64 of the bypass62 the air pressure within the tank i3 is at substantially forty poundsper square inch, whereby the motor I2 is shut-down by the action of theair pressure control l4. The tank I3 is thus supplied with water fordelivery at a maximum pressure of about forty pounds per square inch.

As water is removed from th tank l3 through any suitable outlet means(not shown) the level of the water 16 in the tank is decreased to inturn effect a decrease in pressure of the air between the water 16 andthe top of the tank. Since the pressure of the air within the cylinder23 above the piston 28 is also at a maximum value of about forty poundsper square inch, when the motor i2 is stopped, the piston structure, onremoval of moor/s1 water from the tank i 3, is moved downwardly by theair pressure acting on the tape! the piston 28. As the piston 21 movesbelow this level or the end 63 of the bypass 62 the air within the space18 is compressed against the water, indicated as 18 in Figs. 3 and 4,which water 18 is trapped within the space 18, When the pressure or, theair in the space 18 exceeds the pressure or the air in the cylinder 23acting on the piston 28, the check valve 38 opens to admit air from thespace 18 and through the tube 29 into the cylinder 23. As the pistonstructure continues to move downwardly. under the pressure of the air inthe cylinder 23, the piston 28 moves below the level of the end 8! ofthe pipe 68, to its position illustrated in Fig. 4. It the pressurewithin the cylinder 23, when the piston 28 is at its position shown inFig. 4, is greater than the pressure within the tank l3 the valve 68opens to feed air from the cylinder 23 to the tank l3.

By virtue of the body of water I8 within the space 18 the piston 21 iscapable of moving against and into the water 19 so as to completelyexhaust any air from the air space 18 into the tube 28 for passage intothe cylinder 23. Should the piston 21 travel downwardly into the water18 a portion of such water will pass through the valve 38 and the tube29 into the cylinder 23, as illustrated in Fig. 4. The piston 21,therefore, is movable against and into the body of water 18, whichfunctions as a non-compressible cylinder head for the piston, so thatall of the air in the space 18 is completely exhausted at each fullstroke of the piston 21 whereby to positively eliminate any dead airpockets within the cylinder 22. Air is thus positively fed into the tankl3, through the tube 28, cylinder 23, and pipes 68 and 88, during eachdownward stroke or the piston structure.

With the parts of the feed device in their positions shown in Fig. 4, itis contemplated that the pressure of the air within the tank l3 be abouttwenty pounds per square inch. At this pressure the control switch I 4starts the motor I2 whereby water is again supplied to the tank l3. Onan upward travel of the piston structure, in response to an increasedpressure in the water tank l3, the piston 21 is moved upwardly from thebody of water 18. The operation of the device then proceeds in all-respects as fully explained above in connection with Figs. 1-4. In thepractice or this inventidn .it is contemplated that the cylinder 22 havea diameter of about twoinches so that when a sub-atmospheric pressure isproduced in the space 18 the valve 49 will open against the weight ofthe water 19 to admit atmospheric air through the water 18 and into theair space there above.

From a consideration of the above description it is seen that theinvention provides a device for feeding air into the pressure tank of anair pressure water supply system which is'comprised of a minimum numberof parts assembled in a compact relation andadapted to be carried as aunit on the pressure tank through a single connection. The device iscompletely operable in direct response to pressure variations in thetank and capable of positively supplying air into the tank, to replenishnormal air losses therein, during each cycle of water removal from thetank. In one commercial embodiment of the invention the cylinders 22 and23 are about eight inches in length, with the cylinder 23 having adiameter of three inches, and the cylinderlz a diameter of two inches.In this embodiment the lower end 83 oi. the bypass 62 is located aboutfour and one-half 6 inches from the closed end 24 of the cylinder 22.Although the invention has been described with respect to a preferredembodiment thereof it is to be understood that it is not to be solimited since changes can be made therein which are within the fullintended scope of the. invention as defined by the appended claims. a

I claim:

1. In an air pressure water supply system including a pressure tank, anair iced device for saidtank comprising a cylinder formed with a pair ofcoaxial cylinder portions of diflerent diameters, and open at theirinner ends, a pair of pistons for said two cylinder portions, a hollowrod connected between said two pistons with its ends open to the outerends or said two cylinder portions, 0. first fluid conduit connectedwith said cylinder between said two pistons and with said pressure tank,a second fluid conduit connected between said first conduit and one ofsaid cylinder portions, a check valve insaid second conduit providingfor a fluid flow from said one cylinder portion to said first conduit, asecond check valve in the end of said rod which is open to the secondone; of said cylinder portions.

admission check "valve in the outer end of said second cylinderportion,and a lay-pass conduit having opposite'ends thereof open to said secondcylinder portion at axially spaced positions thereon, with said pistonsbeing movable together in response to pressure changes in said pressuretank.

2. In an air pressure water supply system including a pressure tank. anair feed device for said tank including a pair of co-axial cylinders ofdifferent diameters, open to each other at their inner ends and closedat their outer ends, a piston structure including a pair or pistons forsaid cylinders and having a fluid passage there in open at its ends tothe outer ends of said cylinders, first means fluid connecting saidcylinders at a position between said pistons with said pressure tank,second means fluid connecting one or said cylinderswith said first fluidconnecting means, a check valve in said second fluid connecting meansopening to said first fluid'connecting means, a second check valve insaid fluid passage opening to said one cylinder, an air admission checkvalve in the outer end of said other cylinder, and a by-pass conduithaving opposite ends thereof open to said other cylinder at axiallyspaced positions thereon, with said piston structure being movable inresponse to pressure changes in said pressure tank.

3. In an air pressure water supply system including a pressure tank, anair feed device for said tank including a first cylinder, a secondcylinder, with said two cylinders being coaxial and having their innerends in fluid communication, and said first cylinder being of a largerdiameter than said second cylinder, a piston structure including a pairof pistons for said cylinders and a fluid conduit extended between saidpistons with it ends open to the outer ends of said cylinders, a checkvalve means for introducing air into said second cylinder adjacent theouter end thereof, a check valve in said fluid conduit for admittingfluid from said second cylinder into said first cylinder, a second fluidconduit connected with said tank and with said cylinders at a positionbetweensaid pair of pistons. a third fluid conduit connected with saidtank and said first cylinder having a fluid check valve therein openingto said tank, and a by-pass conduit for equalizing the pressures actingon opposite sides of the piston in said second cylinder, having theopposite ends thereof open to said second cylinder at positions spacedaxially of said second cylinder, with said piston structurebeing'movable in response to pressure changes in said pressure tank.

4. In an air pressure water supply system including a. pressure tank, anair feed device for said tank comprising a single closed cylinder havingtwo portions of different diameters; a piston structure for said twocylinder portions including a first piston for the cylinder portion oflarger diameter and a second piston for the cylinderportion oi smallerdiameter, a fluid passageway in said piston structure having its endsextended through said pistons for fluid communication with said cylinderportions, a first fluid conduit connected with said mall cylinderportion between said two pistons and with said pressure tank, a secondfluid conduit connected between saidlargecylin r portion and said firstfluid conduit and havin a checkvalve therein opening to said tank, asecond check valve carried in said fluid passageway at said secondpiston and opening to said fluid passageway to admit fluid from saidsmall cylinder portion into said large cylinder portion, an airadmission check valve in the closed end of said small cylinder portion,and fluid by-pass means having its opposite said pressure tankcomprising a single cylinder closed at its ends and having a largecylinder portion and a small cylinder portion open to each other, afirst piston f or said large cylinder portion and a second piston forsaid small cylinder portion, a piston connecting tube extended throughsaid pistons to fluid connect said two cylinder portions, with said tubebeing in a spacedrelation within said cylinder, a first fiuid -conduitconnecting the space between said two pistons with said pressure tank, asecond fluid conduit connecting said large cylinder portion with saidpressure tank and having one end intermediate the ends of said largecylinder portion, a check valve in said second fluid conduit opening tosaid pressure tank, an air admission check valve in the closed end ofsaid smallcylinder portion, a fluid admission check valve in the end ofsaid tube extended through said second piston, and a fluid by-pass meanshaving its opposite ends open to said small cylinder portion at axiallyspacedpositions thereon, with said pistons being movablein response tothe pressures in said pressure tank to provide for the actuation of saidcheck valves.

SWAN OSCAR CARLSON.

REFERENCES CITED The following references are of record in the ends inaxially spaced positions on' said small cylso m of t patent;

inder portion, with said piston structure being movable in response tovariations of the pressure in said pressure tank.

5. In an air pressure water supply system including a pressure tank, anair feed device for 35 2,384,770

UNITED STATES PATENTS Number Name Date 1,108,894 Frey Sept. 1, 1914 RuthSept. 11, 1945

